A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging

PURPOSE: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. MATERIALS AND METHODS: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. RESULTS: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. CONCLUSION: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

[Evaluation of noise pollution in Sari [2007-2008]]

Noise is one of the most harmful factors in the environment. It is also one of the harsh phenomenons in this century that people are exposed to. Exposure to noise higher than threshold limit value could cause some physical and mental disorders. High traffic flow due to recent increase in number of vehicles causes higher noise pollution. There are few studies regarding the evaluation of noise pollution in the environment in some Iranian cities. Thus, it is necessary to measure sound pressure level and other related parameters for noise pollution control. Identification of the effective factors on noise pollution is the best approach for promotion of individual, as well as, public health and safety. The aim of this study is to evaluate the noise level in the city of Sari. There exist various methods for calculating the equivalent noise level regarding to noise measurement period. The most ordinary method is DL [day average sound level], that takes 15 hours of sampling [7 am- 10 pm], based on regulations that was approved by the National Environmental Protection Association in year 2003. This method was used for evaluation of noise level in this study. In the first stage, sampling locations were selected, followed by measuring sound levels at the height of one's hearing zone [1.6 m above the ground surface]. A calibrated sound level meter [Model Cell-490, Casella CEL, England] was used for all measurements. The SPSS software V.I5 was used to perform T-test analysis. The results showed that the mean [SD] DL was 75.52 +/- [4.41] dB. The minimum and maximum sound pressure levels during the sampling period were 47 dB and 121.5 dB respectively. Due to the measurement of various circumstances, some times, and also, sampling locations, measure sound pressure level was high. The mean sound level during the daytime period was higher than the national standard levels. Therefore, environmental noise control is the best approach for the prevention of noise related to adverse health effects

Pediatric unintentional injuries in North of Iran

Since the beginning of the 21[st] century, injury has been the most serious public health problem that children face with. The aim of this study was epidemiologic evaluation of unintentional injury in north of Iran. In a prospective cross-sectional study between September 2005-July 2006 we studied data of 347 trauma patients aged 14 years and younger, including sex, age, trauma mechanism, transportation facility, anatomical sites of injury, severity of head injury according to GCS [Severe: 3-8, Moderate: 9-12, Mild: 13-15], injury severity score [ISS], and length of hospital stay [LOHS]. SPSS 13 and independent t-test were used to analyze of data. Out of 3605 trauma patients, 353 were 14 years old or younger with a mean age [SD] of 7.6 [4.0]; Male to female ratio about 2:1. Most of them [42.9%] were 1-5 years old. In patients younger than 1 year, falling was the most common [52.2%] mechanism of trauma while in other groups, traffic accidents were the leading cause of injury. About half of the patients were transported to hospital by their families or other people. About 77% of them suffered from head injury. Mean [SD] ISS was 4.3 [6.6], about 12% had severe injury and it was more than 25 in about 3%. Mean [SD] LOHS was 5.1 [8.9] days. Occurrence of falling and traffic accidents in children is remarkably high. Mainly traffic accidents are preventable. We suggest paying more attention to safety education in all levels of community